01 -
Preheat the oven to 175°C (350°F).
02 -
Slice the Yukon gold potatoes into thin, uniform rounds, approximately 3 mm thick. Place the sliced potatoes in a bowl of water to prevent oxidation and browning.
03 -
In a large saucepan or Dutch oven, cook the ground beef, diced yellow onion, and minced garlic over medium-high heat. Break up the beef as it cooks, stirring frequently, until it is thoroughly browned and the onions are softened. Drain any accumulated excess fat from the pan.
04 -
In a separate mixing bowl, whisk together the condensed cream of mushroom soup, half and half, onion powder, kosher salt, and fresh cracked black pepper until the mixture is smooth and well combined.
05 -
Lightly grease a 23x33 cm (9x13 inch) baking dish. Arrange half of the thinly sliced potatoes evenly across the bottom of the dish. Follow with a layer of half of the cooked beef mixture, then half of the shredded Colby Jack cheese, and finally, half of the creamy sauce. Repeat these layers, ensuring the final layer on top is the remaining shredded cheese.
06 -
Cover the baking dish tightly with aluminum foil. Bake in the preheated oven for 70 minutes. After 70 minutes, remove the foil and continue baking uncovered for an additional 20 minutes, or until the top is golden brown and the casserole is bubbling vigorously.
07 -
Allow the casserole to rest for 15 minutes after baking before slicing and serving warm. This resting period allows the layers to set and prevents it from falling apart.